Air compressor; pressure switch

[Gamble]

So my air compressor pressure switch leaks. Probably because it looks to be the wrong switch? I don't know, but where can I get a new one that is inexpensive?
My dad gave me one but it doesn't have a switch and I don't want to ghetto it up, I want it to be normal. I only run it up to about 100psi, never really need anything higher.

 

[bsaint]

It leaks only when its off?

 

[Gamble]

Yes I believe so.

 

[stonesfan68]

Try Grainger, but you'll need to know the pressure and amp rating of the switch that you need.

 

[Zrexxer]

So my air compressor pressure switch leaks. Probably because it looks to be the wrong switch?

What makes you think it's the wrong switch?

 

[jcm44]

This may work if your motor is the right size:

http://m.northerntool.com/northernt...mId=16151&categoryId=&path=&productName=false

 

[bsaint]

If it only leaks when its off, its the in tank check valve.

 

[Morrisman]

So my air compressor pressure switch leaks. Probably because it looks to be the wrong switch?

Is it an air fitting leaking? Can you remove and seal it with tape or some thread seal goo?

 

[bsaint]

I guess the next question is does it start up funny lately, like really slow or tripping the breaker?

 

[rlitman]

If it only leaks when its off, its the in tank check valve.

^^^^ This!

Your pressure switch should be between the pump and check valve. It is supposed to release all the air in the pump when the motor stops. That is called the "unloader", and it will make a hissing sound when the motor stops.

 

[Gamble]

Yep that is what it does.
It also doesn't have the cover so it you see the spark when you turn the switch on/off. So I wanted to replace it for safety reasons.
Got it used so who knows what the last guy did.

Starts up just fine but it did start up slow once or twice after using the sand blast cabinet and tripped the circuit.

 

[RangerDaleXp]

So my air compressor pressure switch leaks. Probably because it looks to be the wrong switch? I don't know, but where can I get a new one that is inexpensive?
My dad gave me one but it doesn't have a switch and I don't want to ghetto it up, I want it to be normal. I only run it up to about 100psi, never really need anything higher.

Try these people....

https://www.surpluscenter.com/sort.asp?catname=air&keyword=AFSP

 

[bsaint]

I design and build custom air compressor controls so I am fairly familiar with the control end of it.

 

[Gamble]

Cool, I'll get a pic for you guys when I get home.

 

[Gamble]

This is what leaks

 

[Gamble]

And it needs a cover

 

[bsaint]

Does it leak while its running or when its stopped or all the time? Via the pressure switch there is no air at the mechanism. It all comes from the check valve. If the mechanism is stuck so its always relieving (which I've never seen), then it will be a pressure switch problem. Other than that it all points to that check valve on the other end where you discharge tube goes into.

 

[Outlawmws]

And it needs a cover

Is it leaking at a fitting, the little pipe or somewhere else? (Spray some soap like 409 and look for bubbles)

 

[bsaint]

Good point. The aluminum pipe could have a vibration crack at the ferrule

 

[sselander]

This piece broke on mine when I was tightening up the fittings (25 years old) on my compressor,
Rather than buying a new pressure switch, I just bought this part.
It is called a pressure release valve. made by Square D.
My original pressure switch was a Furnas. The switch fit fine, with a couplee of washers to properly fit it like the original.
Use the yellow teflon tape for the fittings.

http://www.drillspot.com/products/44520/Square_D_9049A56_Pressure_Release_Valve

 

[Gamble]

Only leaks when it's off. If you look at the first pic it leaks where the hole is and you can see the spring in there.
Is this something I can pick up at harbor freight, menards or home depot? I rather just pick it up locally and fix it. Also where can I buy a new plastic cover?

 

[Morrisman]

Only leaks when it's off. If you look at the first pic it leaks where the hole is and you can see the spring in there.
Is this something I can pick up at harbor freight, menards or home depot? I rather just pick it up locally and fix it. Also where can I buy a new plastic cover?

You probably can't hear it leaking when it is on, or maybe the pressure causes it to seal.

Pull it apart, it may just need an O ring in, or has some dirt in the seal surface.

 

[Gamble]

Cool, I'll check it out later today, thanks.

 

[JustBob]

That is an unlaoder valve(red arrow), and it is OPEN when the unit is off. It is actuated by the pressure switch... closed when running and open when the compressor cycles off to release pressure from the pump for easier starting. When the unit shuts off you should hear a brief rush of air coming out of the unloader valve, that is the unloader working correctly. Since the valve is suppose to be open then your leak is in the check valve(yellow arrow).




Even if the unloader valve leaks when running, you would not need to replace it unless it was more than a small leak.

 

[Outlawmws]

Only leaks when it's off. If you look at the first pic it leaks where the hole is and you can see the spring in there.
Is this something I can pick up at harbor freight, menards or home depot? I rather just pick it up locally and fix it. Also where can I buy a new plastic cover?

It's supposed to leak for a time when the comp in off; does it stop leaking after a few minutes? What is is doing is emptying the big tube between the pump and the one way valve at the tank so the pump doe not have to start against full pressure.

Edit: Just bob types faster than I do...

 

[Gamble]

It leaks until it's empty. Ok so I now know I need a check valve, I just thought it was the other piece lol
Are these universal or specific sizes? Home depot have them?

 

[JustBob]

It leaks until it's empty. Ok so I now know I need a check valve, I just thought it was the other piece lol
Are these universal or specific sizes? Home depot have them?

First I would pull the check valve out and see if it is bad or not, could be some debri keeping it from sealing. If it needs replacing, you could get the check valve and the switch cover from here... http://www.searspartsdirect.com/partsdirect/index.action just type in your model number and search for the parts you need.

 

[bsaint]

Its probably cheaper from amazon and still made by Conrader But if you want OE perfect fit, Id go with a sears part and part number.

 

[sselander]

The in-tank check valves are pretty generic.
You just need to match the thread sizes.

My 25+ Sears (Campbell-Hausfeld) compressor had an aluminum check valve, price was 35 from Sears.

I ordered a replacement brass one from here, and just needed to put a plug in the hole for the unloader valve tube. My unloader valve tube goes to the air compressor head like they used to do it.

http://www.compressor-source.com/Air_compressor_check_valves_s/25.htm

Some check valves may have a built in unloader valve, but I believe these are not as common. They are called Load Genie's.

http://www.airtekltd.com/valves.htm

 

[KMinAF]

These guys will have what you need:
http://www.maddoxair.com/